1. Technical Field
The present invention relates to a method and apparatus for converting a film image (e.g., a movie) into a television (TV) image, and more particularly, to a method and apparatus for converting a film image into a TV image, which adds a pull-down field based on header information of a TV interface when BT601, BT656 and BT1120 are used as standards for the TV interface, thereby improving accuracy and reducing load of the apparatus when a film image is converted into a TV image.
2. Description of the Related Art
As is well-known to those skilled in the art, a film image must be converted into a TV image in order to display the film image of 24 frames per second (fps) on a TV. That is, a film image is converted into a TV image in order to show a movie on a TV.
One example of techniques for converting film images into TV images is disclosed in Korean Patent Publication Nos. 10-1994-8493A, 10-2004-23011A, etc.
In general, a TV image is transmitted as divided into an odd line image and an even line image, as shown in FIG. 1. The images transmitted as the odd line image and the even line image are combined into one image (i.e., a frame) and displayed at a receiver side.
Under the PAL/SECAM scheme, a TV image includes 25 fps and thus a 2:2 pull-down method wherein one pull-down field is inserted every 12 frames is employed. Under the NTSC scheme, the TV image includes 30 fps and thus a 3:2 pull-down method is employed.
The US and other countries employ a frequency of 60 Hz and transmit a 29.97 fps TV image. In order to use the film image as a video signal for the TV, 24 frame images must be converted into 30 frame images (accurately 29.97 frames) through the 3:2 pull-down method.
Therefore, in order to display the film image of 24 fps on the TV, every four film frames must be converted into five TV frames by the following calculation.
      23.976    29.97    =      4    5  
As shown in FIG. 1, frames consitituting a TV image include two images called fields. One image is an odd line image of the TV image, and the other image is an even line image of the TV image.
If every four frames constituting a movie (or film) image are respectively called A, B, C and D, the following conversion may be performed to display the film image on the TV.
That is, Frame A may be converted into three fields for the TV image. Further, Frame B may be converted into two fields for the TV image. Frame C may be converted into three fields for the TV image, and Frame D may be converted into two fields.
Such conversion may be written as “A-A-A-B-B-C-C-C-D-D” or “3-2-3-2” or simply “3-2”. For this reason, conversion from the film image into the TV image is called “3:2 pull-down”.
Then, the TV image fields are arranged as above with regard to every four frames of the film image. Accordingly, as shown in FIG. 1, the four frames of the film image are converted into five frames for the TV image.
However, such a conventional technique for converting frames of the film image into frames of the TV image has problems of imposing a load on the apparatus while lowering accuracy.